1. Field of the Invention
The present invention relates to an aided design apparatus, an aided design method, and a recording medium for recording a program for carrying out the method, which utilize three-dimensional CAD data or the like to allow an efficient simulation of transportation of a sheet-like member such as paper or film in a copying machine, a laser beam printer, an inkjet printer, a card printer, a facsimile machine, or the like.
2. Description of the Related Art
Recent improvements in the performance of computers have resulted in a rapid shift of CAD (computer aided design) used for machine designing tasks from two-dimensional CAD to three-dimensional CAD. Further, it has recently become common to verify, using a simulator, the design of a machine using three-dimensional CAD data created before the fabrication of the machine.
For example, in designing an apparatus such as a copying machine, a laser beam printer, an inkjet printer, a card printer, or a facsimile machine, in which a sheet-like member such as paper or film is transported, it is desired to verify a design for transporting the sheet-like member (hereinafter referred to as “paper transport design”) before the apparatus is actually fabricated.
When a paper transport design is verified, the designer models a paper transport system unit on a three-dimensional CAD basis and defines a principal section of the paper transport system units and cuts a section of the paper transport system units to create a two-dimensional drawing on the section. Thereafter, the drawing is added with parameters required to simulate paper transportation such as those associated with a paper transport path, a sensor, a transport roller, a transport guide, a film guide such as polyester film, and a flapper. Then, the designer passes the created drawing to persons in charge of various types of analysis as design information.
An actual simulation or analysis of paper transportation is carried out after inputting the shapes of the transport guide, transport roller, and so on again on a simulation program based on the passed drawing (design information) and defining parameters such as the material of the transport guide and a pressing force of the transport roller as attributes of them. The person in charge performs the simulation of paper transportation based on the input information, evaluates analysis results, and provides the designer with feedback of the analysis results to allow evaluation of the functions of the unit.
Alternatively, a simulation of paper transportation may be carried out by outputting three-dimensional shape information in the form of an intermediate file according to STEP (standard for the Exchange of Product Model Data) or IGES (Initial Graphic Exchange Specification) from a three-dimensional CAD apparatus and by using the output data instead of using a drawing as described above.
In this case, the shape information is first passed to a simulator using a data conversion format, and parameters required for analysis such as the pressing force of the roller, the paper pass path, the material of the transport guide plate, and sensor characteristics (delay and chattering) are thereafter individually defined on the simulator. Alternatively, attribute values that depend on materials may be checked on and input from a parameter reference table (which shows materials and frictional coefficients thereof or materials and Young's modulus thereof, for example). A simulation is thereafter performed, and results of transportation analysis are obtained.
As an example of this approach, Japanese Patent Application Laid-Open No. 2001-84018 discloses an aided design apparatus having a mechanism for simultaneously exchanging shape information and processing information with a CAM (Computer Aided Manufacturing) program, in which model data associated with manufacturing processes on a surface or specifications of the surface are provided in the form of color attributes. However, Japanese Patent Application Laid-Open No. 2001-84018 discloses nothing about exchange of data relating to various parameters required for a simulation of paper transportation.
In three-dimensional CAD, shapes and attributes may be managed by using the shapes as modeling tools and using a management tool, which is a separate tool in general, for the attributes. The management tool is a so-called PDM (Product Data Management) system with which all information associated with designing and development of an industrial product is managed on a centralized basis at steps for developing the product to improve efficiency of the steps and to reduce the period of the development. The system is configured to primarily provide functions such as management of data associated with designing including drawing data such as CAD data and document data such as specifications and cooperation between management of configuration data of components of which the product is made up and a purchasing and inventory system and work-flow management for allowing understanding of designing and production schedules and improving the efficiency of those tasks. The system allows centralized management of all information associated with the product.
However, the above-described technique according to the prior art still has many problems to be solved in order to verify effectiveness of a design of a paper transport system unit through a simulation without actually fabricating the machine. Further, it is not appropriate to say that simulations based on design data thus created have been effectively conducted up to the present.
For example, in order to analyze the quality of a design of a transport system and problems with the same, it has been necessary to convert information input on a three-dimensional CAD basis into two-dimensional CAD information temporarily, to select parts and elements associated with the transport system based on the converted two-dimensional CAD information thereafter, and to construct a simulation based on required members thus selected.
Further, much man-power and time is required to understand which part shapes are associated with a transport system from complicated drawings whether they are on a three-dimensional CAD or two-dimensional CAD basis. In addition, one must be highly skilled in transport systems to be able to select those shapes.
Therefore, in order to conduct an accurate simulation in a short time, a problem to be solved remains in that such a simulation depends on the ability of the person in charge of the task and takes much time.
The use of an intermediate file for data conversion allows shape data to be accurately passed to a simulator without creating a two-dimensional drawing. However, there is no intermediate file format that can be commonly used for exchange of parameters required for verification on a simulator such as the material of a transport guide and the pressing force of a roller.
Therefore, while the shapes of members and elements can be passed to a simulation program, parameters of the respective elements must be separately defined and input on the simulator.
Improvements are therefore still needed in that the definitions and inputs can be different from intentions of the designer and in that condition setting can become complicated with an increased possibility of setting errors when the elements are related to each other in a complicated manner, although the complication is not so severe in the case of a simple transport system.
Further, information on solid-state properties such as frictional coefficients must be defined during the simulation by referring to a table of correspondence between materials and frictional coefficients which has been obtained through experiments, which has resulted in similar errors in reading values and has involved man-hour required for making reference as well.
In addition, when there is an error in inputting a parameter, simulation and analysis results that are completely different from the reality can be returned to the designer, which has resulted in a possibility of a design reflecting unnecessary considerations (over-fulfillment of specifications) or a possibility of designing and manufacture of a machine which does not satisfy the specifications in practice. This could result in an increase in the manufacturing cost or a tremendous cost to recover the failure.
When a simulation is attempted again after a design change, a problem has arisen in that parameters must be redefined on the simulator after performing the shape converting operation.
In the case of an appropriation of a design, while shape information which has been modeled for the previous type of the machine can be diverted, parameters are not managed along with the shape information on a centralized basis. This has resulted in a need for checking the parameter values of the previous type of the machine after conversion of a shape file or picking up each of the values from experimental data again. In either case, it has been necessary to redefine required information.
When a designer of the mechanism of a paper transport system attempts to transfer mechanical information to a software developer such as a firmware designer, if the software developer has no mechanical CAD, the mechanical information must be transferred by creating a two-dimensional drawing in the same way as described above and outputting it on paper using a printer or plotter. In this case, since a software developer such as an engine firmware designer reads the information from the two-dimensional drawing thus created on paper, there is a high possibility that a long time is spent before parts constituting a unit are understood; errors occur in reading dimensions in the drawing; and definition errors occur. This has resulted in the possibility of a reduction in efficiency and a cost increase.
Furthermore, simulators associated with paper transport systems on the market take various forms depending on their purposes and applications, e.g., observation of behavior of paper taking the solid-state properties of the paper and the solid-state properties of a transport guide into consideration and checking of sequence control over paper transportation in cooperation with a control tool. This results in a need for changing input parameters and for inputting various parameters for each simulation program depending on the purpose and application.
As a result, simulator parameters values must be separately managed and input on each of simulator programs even when they serve the same paper transport unit, which has sometimes caused problems with maintainability of the parameters.
The above-cited Japanese Patent Application Laid-Open No. 2001-84018 discloses a CAD/CAM apparatus invented to solve problems that occur in the aspect of transfer of design information. In the disclosure, design information is passed to the CAM using a color attribute as a key instead of passing a parameter directly. Specifically, a color conversion table is provided to store information that each color means, and the CAM interprets information added by a design by finding a match between the table and the color attribute serving as a key.
Therefore, the color table is always required when a color attribute is passed from one system to another, and the meaning of the color attribute cannot be understood and transferred as accurate information without the color table.
The variety of input contents increases with the number of parameters, which has resulted in the possibility that an input cannot be rendered using only the color table.
Obviously, Japanese Patent Application Laid-Open No. 2001-84018 only describes that only model data which are associated with a manufacturing process performed on a surface or the specifications of the surface are added as color information.
Another possible approach is to employ PDM to manage parameters values for analysis and to connect a simulator to the system for cooperation. However, problems may be caused by straightforward introduction of PDM in practice because it results in a cost increase from the viewpoint of capital investment; the system becomes complicated as a whole; and designers and evaluators may conduct complicated operations and management.